This invention relates to a secure locking mechanism particularly but not exclusively for a housing of a coin freed mechanism.
Coin freed devices are used to operate various different types of equipment. In some cases such as vending machines the machines are often placed in a location which enables them to be watched over by responsible persons to reduce the likelihood of attempts to break open and steal the contents. In such cases it is desirable to provide a suitable locking arrangement and security container but in many cases these are not particularly complex or strong since the positioning of the equipment tends to inhibit attempts of theft.
In other cases such as car wash equipment, the coin freed devices are located in an area which is generally not supervised and hence the container for the coin freed device must be manufactured in a manner which itself inhibits attempts at theft.
One problem which arises with devices of this type, and also with other locked devices is that of attempts to force the lock by pounding it centrally with a punch to force the lock barrel out of its seating.
It is one object of the invention therefore to provide a lock guard device which can be used to protect a key operated lock against unauthorized forcing of the lock.
According to the invention there is provided a lock mechanism comprising a lock actuating device, a lock member engageable by an elongate blade of a key, said lock member having a [slot shaped] slot-shaped front opening for movement along an axis into the lock member of the blade of the key when pressed through said front opening, said key blade being shaped to have one dimension transverse to its length longer than s dimension at right angles thereto so that it can pass through the slot-shaped front opening, said member and key being arranged such that a matching key can be rotated to move the lock actuating device, and a security cover device for covering the front opening, said security cover device comprising a collar member for surrounding said front opening and defining a cover opening forward of and axially aligned wit said front opening a cylindrical wall extending from said cover opening to said front opening, and lip means on said cylindrical wall at said cover opening, said cylindrical wall having a circular cylindrical inner surface surrounding said axis, a front plate member received within the cylindrical wall generally at right angles to the axis and free to rotate within the cylindrical wall about the axis, said front plate member having a slot-shaped opening therein for the key, said lip means confining the plate member within the cylindrical wall against axial movement out of the cover device, and at least three rigid spherical balls separately and freely mounted in an area defined rearwardly of the front plate and inwardly of the cylindrical wall, the balls being free to move radially within the confines of the cylindrical wall and to rotate around said axis, the balls being dimensioned relative to the cylindrical wall such that, when the balls are moved in an outward direction to a parted position sufficient to just allow the blade of the key to pass through a slot shaped opening closely defined between the balls, the balls are restrained from further movement in the outward direction by contacting the cylindrical wall.